My argument, and interpretation is that:It's a Special Attack, which has NO attribute attached to it, THUS cannot miss, but does NO direct Damage. It has NO possibility to deal any direct damage, it ONLY applies the FIRE debuff to anything within the Spray effect area.

The Counter argument argues that Special "Attacks" automatically roll and thus do direct damage, as he selectively read the Special Attack section in the rules.

13 - Special AttacksA special attack is denoted by . The number is how manyaction points you must spend to make the special attack. Youmust spend all the action points indicated at once in order forthe special attack to work.If a special attack lists no distance or area of effect, it may onlytarget enemy models in melee. If a model possesses a distanceeffect as a special ability they may use it with any special attackthey take, unless the action specifies otherwise.Any dice the special attack grants are in addition to the model’snormal attribute.If a model has a special ability that causes status effects (such asFire), any special attack that model uses will also cause the statuseffect if they successfully deal damage.Unless the attack indicates otherwise, its effects expireimmediately following the resolution of the special attack.

The most recent RED part is that part he keeps quoting, saying that it has to deal damage to apply the FIRE Debuff.

Please, PLEASE tell what the TRUE use of this special attack is.

Keep in mind Special Attack is literally only a name to differentiate between it and a Special Ability, since both can be affected individually. While Special attacks are offensive in nature, it does not add dice or do any direct damage unless the text in the Special Attack states it does.